1. Field of the Invention
The present invention relates to a steering device.
2. Description of Related Art
There has been proposed a steering device that, with a lock mechanism (fastening mechanism) unlocked by an operating lever, allows tilt adjustment of adjusting the position of a steering wheel by tilting a steering column and telescopic adjustment of adjusting the position of the steering wheel by sliding a movable jacket of the steering column in the axial direction (e.g., see Japanese Patent Application Publication No. 2014-213691).
The fastening mechanism has a first cam, which is integrally rotatable with the operating lever, and a second cam, which is not rotatable but is movable in the axial direction, both disposed on a fastening shaft, and includes a motion conversion mechanism that is able to change the axial dimension of both cams as a whole. When the first cam is rotated by the operation of the operating lever, the second cam is moved in the axial direction and fastens a vehicle body mounting bracket to a column fixing bracket. As a result, lock is achieved.
A boss of the second cam has a rhombic cross-section (see JP 2014-213691 A) or a rectangular cross-section (see Japanese Patent Application Publication No. 2008-307959). During tilt adjustment, one pair of opposite flat parts of the outer periphery of the boss slide inside a tilt-adjust long groove provided in the vehicle body mounting bracket. During telescopic adjustment, the other pair of opposite flat parts of the outer periphery of the boss slide inside a telescopic-adjust long groove provided in the column fixing bracket.
However, when telescopic adjustment is made to extend a steering shaft (pull the steering wheel) with the lock mechanism unlocked, the boss of the second cam may rotate due to friction with the upper edge of the telescopic-adjust long groove and get caught by sticking like a wedge in the telescopic-adjust long groove. In that case, telescopic adjustment for extending the steering shaft requires a larger operating force, and can no longer be made smoothly.